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Sanibel rice rat study to wrap up next year

By Staff | Aug 2, 2017

Wesley Boone holds a Sanibel rice rat. PHOTO PROVIDED

To learn more about the elusive Sanibel rice rat, J.N. “Ding” Darling National Wildlife Refuge, the Sanibel-Captiva Conservation Foundation, City of Sanibel and researchers from the University of Florida have partnered up to study the subspecies which is listed under the Endangered Species Act.

The study, which has been funded by the Florida Fish and Wildlife Conservation Commission, began two years ago. Wesley Boone, a PhD student studying wildlife ecology and conservation at the University of Florida and who is also one of the main researchers of the Sanibel rice rat study, said that so far, they have found out that they are hard to catch and that they thrive in very inhospitable environments where it’s hot, humid and buggy. The rice rats make their home in the wetlands on Sanibel.

Although rice rats are found all over Florida, the Sanibel rice rats are found only on Sanibel. Boone said this is due to isolation.

“The distance between Sanibel Island and the mainland means there is likely no movement between the island and mainland populations, allowing for a gradual accumulation of genetic mutations that vary from the mainland populations,” he said.

According to Florida Fish and Wildlife Conservation Commission, the Sanibel rice rat grows to be about 10.1 inches and has dark fur on its back side, a dark white belly and white feet. In the wild, they typically live less than one year.

Boone uses a Sherman live trap to study the rice rats. PHOTO PROVIDED

Boone said that the rice rats are largely carnivorous animals.

“Although they will and do eat vegetative matter, they consume snails, mollusks, small fish, minnows, fiddler crabs and macroinvertebrates. As with any other secondary consumer, they shape the system by removing primary consumers,” Boone said.

Some of their predators are snakes, bobcats and coyotes.

“They’re crepuscular (which means) mostly active at dawn and dusk, so hawks aren’t a major factor,” Boone said.

But, the biggest threat to the rice rats Boone has found, are humans, both directly and indirectly.

“Every new development on Sanibel takes away from their potential habitat. Every new road further fragments their remaining habitat and potentially leads to road mortalities (roadkill). Additionally, Sanibel has experienced drastic changes over the last 50 plus years. What once was a grassland, is now covered in shrubs (buttonwood). The water table is highly modified so that fresh water is available for residents in the dry season, but also so that yards don’t flood in the wet season. This changes everything, from what plants occur where, to the abundance and diversity of prey species. Finally, it is a scientific fact that the seas are rising, and the best supported scientific theory is that this is the product of human actions. If rising seas envelope Sanibel, the Sanibel Island rice rat will likewise perish, or only persist in zoos. Without public support, this and thousands of other species are headed for extinction,” Boone said.

Boone studies the rice rats for four months out of the year. He comes down to Sanibel for two months in the summer and for two months in the winter. Right now, he has two interns that assist him with field work.

“In the winter its just me, except for an occasional volunteer. The work is harsh, so quality volunteers are hard to come by and our grant doesn’t include funding for assistants,” Boone said.

Boone said he uses Sherman live traps to study the rice rats which he places all over Sanibel. He prefers these traps because they are affixed to a floating board that rises and falls with tides and rain water. The boards move up and down a wooden dowel so they can’t float away. The most Sanibel rice rats Boone has caught is 27 during a single field season. On average, he and his team catch about 10. He still isn’t sure about the total number that are living on Sanibel.

Boone works seven days a week for 8-10 hours each day, two months straight. Some daily challenges for him include walking through deep water, facing alligators and mosquitoes, dense vegetation, summer heat and humidity, wasp nests and honeybee hives hiding in downed palms.

“We leave the house at sunrise, then check traps and process animals for 3-4 hours. Processing animals is done in the field and involves weighing, aging, sexing, observing breeding status, and giving each animal a uniquely numbered ear tag. We then release the animal where it was caught. We then break down old trap grids, set new grids, measure vegetation around each grid, and repair equipment. Field days in the winter, when I’m solo, frequently cross 12 hours. Each night, I enter data, read papers and communicate with our many collaborators. Plus study. Study statistics, research design, scientific writing, genetics, etcetera. This is grad school after all,” Boone said.

The field research which is being done to better understand the Sanibel rice rats, will conclude next year.

“We plan to finish the field research component in February 2018. Then its back to the University of Florida to analyze the data, create management plans, and publish the results. It’s a long process, but this process guarantees that we implement the most ecologically and physically responsible management plans that we can. Funding for conservation is very limited, so we want to make sure it is used effectively,” Boone said.